Behavior of tetracycline and polystyrene nanoparticles in estuaries and their joint toxicity on marine microalgae Skeletonema costatum

Catégorie : Impacts de la Pollution Plastique
Date :29 juin 2020
Avis TSC : Les particules de plastiques apportent leur pollution propre associée à la chimie de leurs formulations, mais elles peuvent aussi jouer le rôle d’adsorbants qui vont fixer des métaux lourds ou des molécules organiques polluantes. Le cas présenté ici concerne l’adsorption des antibiotiques de type tetracycline sur des nanoparticules de plastiques en phase aqueuse. Ce phénomène est bien présent dans l’eau douce et il est accentué quand la salinité augmente. C’est-à-dire que les particules auront plus d’affinité pour l’antibiotique qui se fixera en plus grande quantité. C’est une nouvelle voie qui vient d’être mise en évidence pour la diffusion des molécules antibiotiques polluantes dans l’environnement marin. L’utilisation massive de ces molécules comme facteur de croissance en alimentation animale et comme médicament en santé humaine rend leur présence très préoccupante dans les eaux de surface et donc maintenant dans les eaux marines côtières.
Feng, Li-Juan; Shi, Yi; Li, Xiang-Yu; Sun, Xiao-Dong; Xiao, Fu; Sun, Jia-Wen; Wang, Yue; Liu, Xiao-Yun; Wang, Shu-Guang; Yuan, Xian-Zheng.
Environmental pollution (Barking, Essex : 1987) : 263 (DocId: Pt A) 114453 (2020).
Polystyrene nanoplastics (PS NPs), which are newly emerging as particulate pollutants, are one of the most abundant plastic types in marine debris. Although there has been extensive research on microplastics, the sorption behavior of PS NPs in surface waters remains unknown. In addition, in the previous joint toxicity studies, the concentration of organic pollutant in the joint system was based on the EC50 of this pollutant, rather than the actually amount of this pollutant adsorbed on nanoplastics (NPs). In this study, the sorption behavior of PS NPs with different surface charges in the surface water of estuaries and joint toxicity of that absorbed tetracycline antibiotic in equilibrium were investigated for the first time. Because of the electrostatic repulsion, salting-out effect, and partition function, the sorption capacity of tetracycline antibiotic by differently charged PS NPs was enhanced with increasing salinity. The biological effects of exposure to tetracycline-saturated PS NPs were complicated, which can be attributed to the surface characteristics of mixtures such as hydrophobicity and charges. Thus, the role of NPs in the natural environment as a carrier of antibiotics may provide an alternative for antibiotic inputs from inland water to coastal marine water, which would not only change the environmental fate and ecotoxicology of antibiotics and NPs, but also pose challenges to the safety of coastal aquaculture and marine ecosystem.